This invention is directed to a novel coupling device for use with a pair of flexible rods for inserting cables into cable-protecting pipes.
It is known methodolgy when inserting cables into cable-protecting pipes to first push an elastic fiberglass rod from one location of the cable-protecting pipe, as for instance from a cable shaft to another desired site. Thereupon the cable to be inserted is fastened to the end of the elastic fiberglass rod which together with the hooked-up cable is pulled back through the cable protecting pipe, and in this manner the cable is passed through the entire inside of the selected length of the cable-protecting pipe. In this manner cables or similar electrical lines can be inserted into tubular protecting pipes which can be either totally empty or partly filled with cables or electric lines.
The problem with such prior art methodology is that the length through which such cables may be inserted is limited for a variety of reasons. As one example, the friction which is generated when the flexible fiberglass rods are inserted into the cable-protecting pipes must be overcome, and this alone is quite difficult (at times impossible). Even if the flexible/elastic rods are of such design and material as to remain generally straight in their "rest" position, they will still bend when inserted into the cable-protecting pipes, particularly if there are other cables or lines therein. Thus, as the elastic rods bend along the length of the cable-protecting pipes, they bear against the inside surfaces thereof at different points and tend to bind. Absent bending, and with pure rectilinear movement it is possible to insert cables into cable-protecting pipes up to lengths of 200 meters. However, under less optimum circumstances, where the cable-protecting pipes are curved, the length of cable insertion and flexible rod insertion is correspondingly less than the aforementioned 200 meters.